1. Field of the Invention
The present invention relates to a dental handpiece, encompassing a gripping sleeve and a head sleeve which is bent relative to the longitudinal axis of the gripping sleeve, as well as a drive shaft which is supported within the handpiece and which drives a treating implement arranged in a head at the free end of the head sleeve, the drive shaft being transversely divided in the region of the bending location, wherein the two drive shaft parts are in interengagement through the intermediary of a follower or engaging device, and wherein a planetary ball gear drive is interposed in the driven drive shaft part.
2. Discussion of the Prior Art
Handpieces of that type are connected to a drive component at the free end of the gripping sleeve somewhat of the type as disclosed in German Pat. No. 12 19 170, so as to be easily detachable. The inventively provided planetary ball gear drive disclosed in the present application, in contrast with other types of drives, for example, a worm gear drive which is known from the disclosure of German AS No. 15 66 291 and which restricts the view of the treating area, forms a safeguard against overloads which is afforded through the use of simple means.
A handpiece of the above-mentioned type is known from the disclosure of German AS No. 26 44 458. In this known handpiece, the planetary ball gear drive of the driven drive shaft part is located in the region at the end of the head sleeve towards the gripping sleeve, and thereby in the region of the bending location of the handpiece, whereby the head sleeve and the gripping sleeve are interconnected by means of a screw-threaded arrangement which, for example, for mounting purposes, are only detachable with difficulty, and as result cannot be manipulated by personnel in the dental practice. In addition thereto, the location of the planetary ball gear drive in the region of the bending location prohibits any detaching between the head sleeve and the gripping sleeve, inasmuch as through such a detaching there would be eliminated the stable engaging relationships of the planetary ball gear drive, as well as the correct association of the drive component, for instance, during the reestablishing of the connection, and thereby produce operational malfunctions of the drive system. It is a frequent occurrence that, because of reasons required by the driving operation and treatment, it is necessary to work with another, for example, smaller head. Heretofore, in order to facilitate the foregoing, inasmuch as the mentioned head sleeve and gripping sleeve are practically inseparable, the entire handpiece had to be detached from the drive component and then exchanged for another complete handpiece which incorporates the desired other head. Consequently, there is obtained a complex bearing support.